1. Field of the Invention
The invention relates to an electric horn structure having a trumpet body and a resonator, and more particularly to the electric horn structure whose trumpet body and resonator is made in one piece. By providing the one piece electric horn structure, the manufacturing process of the electric horn can be simplified, the cost can be reduced, and the sound quality of the electric horn can be improved.
2. Description of the Prior Art
As well known in the art, an electric horn is a kind of sound conveyor. Referring to FIG. 1, a typical electric horn 1 has a resonator 11 which is circumambiently wrapped by a metal coil 10 and with one end installed onto an extruding central shaft 120 of an electromagnetic base 12. The other end of the resonator 11 is then adhered to a trumpet body 13 which includes an adhered seal plate 14 in the center located close to the end adjacent to the resonator 11. While applying the electrical power to the electric horn structure, the resonator 11 wrapped by the metal coil 10 will be induced and vibrate around the central shaft 120 of the electromagnetic base 12. As the resonator vibrates, sound waves with various frequencies will be generated and propagate outwards through the trumpet body 13. Thus, audible sound is generated by the electric horn 1.
Obviously, the resonator 11 and the trumpet body 13 are two major parts in the electric horn 1 for sound generating. Thus, the manufacturing and the material for these two parts are especially crucial in the quality of the electric horn 1. Referring now to FIG. 2, the manufacturing process of a conventional resonator 11 includes utilizing a metal or non-metal sheet to roll into a hollow cylinder shell 110 with a proper outer diameter, and applying a paper sheet 11 onto the outer surface of the hollow cylinder shell 110 by a layer of glue 112 to stabilize the profile of the hollow cylinder shell 110. On the other hand, the inner diameter of each cross section of the trumpet body 13 tapers to an inner diameter slightly larger than the outer diameter of the resonator 11 at the extended edge 130 of the trumpet body 13, no matter what kind of material (paper or metal) is used for the trumpet body 13 and which the extended edge 130 is thus formed an outside covering connection to the resonator 11. While connecting the trumpet body 13 and the resonator 11, a layer of gum 15 is applied between the extended edge 130 and the resonator 1 for joining the trumpet body 13 and the resonator 11 into a unit. The trumpet rim 131 at the larger diameter end of the trumpet body 13 is adhered by a buffer plate 16. By providing the buffer plate 16, the trumpet body 13 can be adhered to the frame 17 of the electric horn 1.
Due to the consideration of the capacity of the electromagnet base 12 and the vibration need, it is critical to select the material and the thickness for every part of conventional electric horn 1. Because the resonator 11 is driven by the electromagnet base 12, the material for the resonator 11 should be as lightweight as possible. Because the trumpet body 13 is used to transform the vibration of the resonator 11 into sound wave, the material for the trumpet body 13 should be as lightweight as possible, too. Conventionally, lightweight material is used to be rolled into a resonator 11, and to be pressed into a trumpet body 13, separately. Then, the resonator 11 and the trumpet body 13 are glue connected. It would seem that the manufacturing of the resonator 11 and the trumpet body 13 is trivial; the process requiring only rolling and pressing. However, the manufacturing work for these two parts is laborious.
In aforesaid description, the hollow cylinder shell of the resonator 11 can't be firmly set right after the rolling process. A paper sheet is applied onto the outer surface of the resonator 11 so that the seam of the cylinder shell can be protected from dislocation and the cylinder shape of the shell can be maintained. Finally, after all these processes, the resonator 11 then can be adhered to the pressed trumpet body 13. As made evident, the conventional manufacturing process for the horn is laborious, and takes at least two gluing steps. Moreover, the assembly of the resonator 11 and the trumpet body 13 from aforesaid manufacturing process has various disadvantages, such as the following.
1. The resonator is wrapped and secured by the paper sheet to prevent from the deformation at the seam of the cylinder shell. However, such a resolution does not only cost in process time, but also achieves very limited strength to bear the vibration from the resonator. If a vibration with substantial energy is excited, it is quite possible that the paper sheet will fail to protect the seam, eventually, and the resonator will be torn apart from the seam. The damage in the resonator will lead to jamming at the junction of the resonator and the electromagnetic base, and consequently no vibration can be induced at the resonator. PA1 2. The resonator and the trumpet body, binded by glue, will undergo cyclic shearing excitation between the glue interface, while in operation, due to the vibration from the resonator, weights and restraints of the resonator, the trumpet body, and all other related parts. The existence of the cyclic excitation will damage the binding between the resonator and the extended edge of the trumpet body and possibly result in the deviation of the induced sound waves. PA1 3. An extremely small eccentricity between the resonator and the trumpet body is essential for a convention electric horn to perform well. An eccentricity over tolerance will definitely jam the resonator motion with respect to the central shaft of the electromagnetic base. Such a high precision requirement in eccentricity does not only cost difficulty in binding, but can also cause a high failure rate in horn assembly due to the manual binding work. PA1 4. The trumpet body of a conventional electric horn is made of thin metal or non-metal sheet by pressing/stamping. Under the pressing/stamping process, the larger diameter end of the trumpet body will become thinner and less stiff which will lead possibly to a noisy sound wave while the horn is at work. The generation of the noisy sound wave is particularly obvious and intolerable in a horn with metal trumpet body. Moreover, the buffer plate adhered to the trumpet rim cannot provide sufficient support and restraint for the trumpet body connecting with the horn frame, so that the noisy sound wave can't be blocked in a conventional electric horn.
Therefore, an invention devoting to resolving aforesaid disadvantages of conventional electrical horn is necessary.